I'm an ambush hunter, and I hunt from the ground, so I know I'm going to be sitting on it, wet or dry, cold or hot. I have been using a foam pad for a long time, and it does all I need. It's 2 1/2" thick, has a shoulder strap, keeps my butt dry and warm for as long as I want to sit. If it's particularly cold, wet and nasty I also take along a wool blanket roll on my back and use that to keep my legs off the ground and to throw over them for a little warmth. I do this even if I'm wearing period kit. Since I am required to wear hunter orange, anyway, I don't worry about the fact that it's modern gear.
Spence
Spence